Knee airbag modules are becoming increasingly common in modern automobile construction. Such a knee airbag module consists basically of a housing, an airbag folded into the housing, and a gas generator connected to the housing. The airbag, which can be inflated by the gas generator, helps to prevent the knee and shin region of the protected occupant from striking against the relatively hard instrument panel, and further has the task of preventing the forward displacement of the occupant's pelvis in a head-on collision. This is especially important for unbelted occupants.
There are two basic concepts for arranging such a knee airbag module in a vehicle. In the first concept, the housing of the knee airbag module is around knee height of the protected occupant, and the opening of the housing points in the direction of the knee or shin. The airbag then basically expands in the direction of the occupant. In a second concept (low mount), the housing is in a lower section of the dashboard or in an adjacent area of the footroom cover. In this case, the housing, which can be made relatively flat, basically horizontal, means that the outlet opening of the housing extends basically horizontally. In this case the fully unfolded knee airbag generally has a “banana-shaped” cross section.
A generic “low mount” knee airbag module is described in De 10 2009 005 993 A1. The knee airbag module of that design has a housing with an upper wall and with a peripheral side wall. The gas generator is arranged nearly entirely within the housing and extends in the proximity of the front section of the peripheral side wall and parallel to the section. A fastening flange extends from each of the two opposite side sections of the side wall. The two fastening flanges serve to fasten the knee airbag module to a vehicle-secured structural component, for which purpose the flanges each have a fastening section, the surfaces of which face toward the vehicle are designated hereinafter as fastening surfaces. The two fastening surfaces are hereby relatively long, with the result that the corresponding vehicle-secured structural components must also have accordingly long fastening surfaces. On the basis of the fact that frequently there is only very little mounting room available, providing the accordingly long fastening surfaces in the vehicle can in many cases be problematic.